I'm new to getting things printed at Shapeways and until today only had 2 test prints in WSF and Alumide which I was really impressed with. Today I received a 2nd order of some actual designed items and was very disappointed with one of the parts I received in Black Strong & Flexible. It's a part with numerous 1mm deep hex shaped pits, many of which I noticed were still mostly or partially filled with powder. I took a small soft brush to clear out some of what I thought was unsintered powder, only to discover that it was actually WSF underneath and the color is just an external coating. This is no where on the material description pages. Is this the same story with all of the non-white strong & flexible materials? Here is the 3d file, and what I received.

Ok, that's fine. But the powder was hardly trapped. It took 10 seconds with an old toothbrush to clean it off and it was obvious that it was there. You could have held it upside down and tapped the back and a bunch would have fallen out. It's strange that they'd put it in the dye in that condition.

If the non-white "strong and flexible" materials are actually just normal WSF dipped in paint
after a quick brushing, I think that this should be stated clearly on the materials page. (This
seems to make them a poorer solution than just washing and (spray-) painting a model after
delivery.)
The current text creates the impression that the process uses appropriately colored starting
materials ("nylon plastic that comes in a variety of colors" and even different maximum
dimensions on the design guide page, just as if these were done on a different machine).

To me, shapeways has had a much more professional appeal than the other low-cost competitors.
(Said as a long-time lurker who just had his first few parts printed). Please keep up your technical
standards (material documentation, terms&conditions WRT pricing scheme, print reproducibility)
before you even consider adding facebook "like buttons" complete with their js tracking code and
other short-lived "community experience" fads.

Coloured S&F is actually dyed using acid dyes (the exact same dyes that can be used for dyeing clothes)
WSF also takes diluted artists acrylic paint rather well, which also has the advantage of sealing the surface.

@eNonsense Shapeways should be able to do a re-print for you, just send in images and ask

Thanks for the clarification. Still this should be somewhere on the materials page.
(Or add a paragraph to the design tips page, somethink like "The black, red and
purple finishes are produced by dyeing the white material after printing with an
acidic dye akin to those used for dyeing clothes. See our tutorial at http://... for
tips on how to paint WSF models yourself.")

I'm more concerned about the quality control however. For a place that allows you to host your own store, it could sure impact the experience your customers have when buying your designs and reflect negatively on you, rather than just on shapeways. It makes you not want to offer your designs in these colored materials, which is really disappointing. Especially considering that again, this could have been prevented by actually looking at the part to notice that it isn't clean and hitting it with a toothbrush for 10 seconds before dyeing.

BTW,
I assume that the Black Fine Detail plastic is also dyed after production, because it's slightly splotchy and is softer than the white (which I know happens in some dyeing processes). I'm happy with these parts though. No complaints, as this splotchiness is apparent and expected by looking at the examples on the materials page.

AFAIK, Black detail is black all the way through. The spotchiness as seen on the material page is probably uncured polymer that can be removed by soaking in a warm weak solution of NaOH (Sodium Hydroxide/Lye/Casutic Soda) followed by rinsing under running water.